Lateral flow tests and lateral flow assays are becoming increasingly useful for clinical diagnostics, veterinary diagnostics, environmental screening, drug screening and food tasting, among other applications. Exemplary lateral flow tests include, but are not limited to, a pregnancy test (i.e., hCG), fertility and ovulation tests (i.e., LH and FSH), infectious disease tests (e.g., HIV, Strep A, H. Pylori, HbsAg, and Mononucleosis), PSA, FP, human haemoglobin faecal and other cancer detection tests, cardiac markers, and drug tests (e.g., amphetamine, cocaine, BZO and THC).
In the past, lateral flow tests were primarily used for qualitative detection (i.e., yes or no as to existence of a selected condition). More recently, lateral flow assays have been developed for quantitative determination. For example, the quantitative determination of individual human proteins in biological fluids such as blood, plasma, serum, urine or cerebrospinal fluid provides an important tool for diagnosing diseases, as well as monitoring the course of diseases and particularly the effect of treatments therefor. Manual visual techniques for facilitating the reading of lateral flow assay results (e.g., selective placement of windows and use of color and indicia to improve viewing of visual test strip indicators) are being increasingly enhanced by automated optical detection systems. Optical instrument configuration and programming is important to achieving reliable and reproducible results. Optical detection systems can employ any of a number of methods such as the use of coated microspheres, superparamagnetic microspheres, remission or retransmission photometry, colorimetric techniques and fluorometric techniques.
An exemplary optical instrument or reader for a lateral flow strip is described in U.S. Pat. No. 6,394,952, to Anderson et al. The patent discloses an assay device in combination with a computer-assisted, reflectance-type reader having data processing software. The data processing software employs data reduction and curve fitting algorithms, optionally in combination with a trained neural network, for determining the presence or concentration of analyte in biological sample. This reader and other similar readers, however, can be relatively costly to implement and inaccurate. The process of inserting a test strip into a reader and removing it therefrom is subject to much variation that can skew test results. A need therefore exists for a reader that compensates for these variations. For example, a need exists for a reader that can detect test strip position therein and facilitate registration of the strip in the reader consistently for optimal reader results.
Optical navigation devices such as optical mouse engines have been developed to detect and track cursor movement in computer applications. In addition to cursor location, some optical mouse engines are provided with an additional function such as video imaging or image scanning. Exemplary optical mouse engines are described in U.S. Pat. No. 6,392,632, to Lee, in U.S. Pat. No. 6,281,882, to Gordon et al, and in U.S. Pat. No. 6,256,016, to Piot et al. None of these existing optical mouse engines, however, has been employed to read test strips for medical test data collection, nor to determine movement of a test strip within the reader to improve consistency of test strip position in the reader and therefore improve the accuracy of test strip results. A need therefore exists for a test strip reader employing optical engine technology that uses the built-in change of position detection in an optical engine to determine test strip position, movement and speed, and to facilitate improved quantitative and/or qualitative data collection using test strips.